Display driver circuit supporting operation in a low power mode of a display device

ABSTRACT

A display driver circuit configured to drive a display panel includes a memory, a decoder, and a controller. The memory stores first data using data from outside of the display driver circuit. The decoder decodes the stored first data. The controller generates compression data using the decoded first data. While an image based on the decoded first data is displayed on the display panel, when second data based on the data from the outside are not stored in the memory after the first data are stored in the memory, the controller controls the decoder such that the decoder does not operate and controls the memory such that the compression data are stored in the memory.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2018-0033421, filed on Mar. 22, 2018 in the KoreanIntellectual Property Office, and U.S. patent application Ser. No.16/150,365 filed on Oct. 3, 2018, the disclosure of which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

Exemplary embodiments of the inventive concept relate to an electroniccircuit, and more particularly, to a configuration and an operation of adisplay driver circuit configured to drive and control an operation of adisplay device.

DISCUSSION OF RELATED ART

Most electronic devices include a display device. The electronic devicemay provide a user with an image through the display device. The displaydevice may be implemented in various forms such as a liquid crystaldisplay (LCD), a light emitting diode (LED) display, an organic LED(OLED) display, or an active matrix OLED (AMOLED) display.

The use of small-sized electronic devices is increasing as ITtechnologies develop. Examples of small-sized electronic devices includesmartphones, tablet personal computers (PC), portable multimedia players(PMP), laptop PCs, wearable devices, and/or the like.

Since most small-sized electronic device operate using power from abattery, it is important to reduce power consumption, e.g., powerconsumption of a display device included in the small-sized electronicdevice.

SUMMARY

According to an exemplary embodiment of the inventive concept, a displaydriver circuit configured to drive a display panel may include a memory,a decoder, and a controller. The memory may store first data using datafrom outside of the display driver circuit. The decoder may decode thestored first data. The controller may generate compression data usingthe decoded first data. While an image based on the decoded first datais displayed on the display panel, when second data based on the datafrom the outside are not stored in the memory after the first data arestored in the memory, the controller may control the decoder such thatthe decoder does not operate and controls the memory such that thecompression data are stored in the memory.

According to an exemplary embodiment of the inventive concept, a displaydriver circuit configured to drive a display panel may include a memory,a decoder, and a controller. The memory may store first data fromoutside of the display driver circuit. The decoder may decode the storedfirst data. The controller may control the memory and the decoder usingthe first data from the outside. When a size of the first data from theoutside corresponds to a size of compression data, the controller maycontrol the decoder such that the decoder does not operate and tocontrol the memory such that an image is displayed on the display panelusing the stored first data without the compression data.

According to an exemplary embodiment of the inventive concept, a displaydriver circuit configured to drive a display panel may include anencoder, a memory, a decoder, and a controller. The encoder may encodefirst data of a first type. The memory may store second data of a secondtype, third data of a third type, and the encoded first data. Thedecoder may decode the encoded first data and the second data stored inthe memory. The controller may receive the first data, the second data,and the third data from outside. When the controller receives the seconddata, the controller may control the encoder such that the encoder doesnot operate. When the controller receives the third data, the controllermay control the encoder and the decoder such that the encoder and thedecoder do not operate.

BRIEF DESCRIPTION OF THE FIGURES

The above and other features will become apparent by describing indetail exemplary embodiments thereof with reference to the accompanyingdrawings.

FIG. 1 is a block diagram illustrating a configuration of an electronicdevice including a display driver circuit according to an exemplaryembodiment of the inventive concept.

FIG. 2 is a block diagram illustrating a configuration associated with adisplay device of FIG. 1 according to an exemplary embodiment of theinventive concept.

FIG. 3 is a block diagram illustrating a configuration of a displaydriver circuit of FIG. 2 according to an exemplary embodiment of theinventive concept.

FIG. 4 is a conceptual diagram for describing a method of processingfull color data to generate compression data and color data in acontroller of FIG. 3 according to an exemplary embodiment of theinventive concept.

FIG. 5 is a conceptual diagram for describing a receive mode and a powersaving mode of a display driver circuit according to an exemplaryembodiment of the inventive concept.

FIG. 6 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving full color data from anexternal device according to an exemplary embodiment of the inventiveconcept.

FIG. 7 is a block diagram for describing an operation of processing datain a power saving mode after full color data are received from anexternal device according to an exemplary embodiment of the inventiveconcept.

FIG. 8 is a timing diagram for describing an operation of a controllerin the receive mode of FIG. 6 and in the power saving mode of FIG. 7according to an exemplary embodiment of the inventive concept.

FIG. 9 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving encoded data from anexternal device according to an exemplary embodiment of the inventiveconcept.

FIG. 10 is a block diagram for describing a method of processing data ina power saving mode after encoded data are received from an externaldevice according to an exemplary embodiment of the inventive concept.

FIG. 11 is a timing diagram for describing an operation of a controllerin the receive mode of FIG. 9 and in the power saving mode of FIG. 10according to an exemplary embodiment of the inventive concept.

FIG. 12 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving compressed data from anexternal device according to an exemplary embodiment of the inventiveconcept.

FIG. 13 is a block diagram for describing a method of processing data ina power saving mode after compressed data are received from an externaldevice according to an exemplary embodiment of the inventive concept.

FIG. 14 is a timing diagram for describing an operation of a controllerin the receive mode of FIG. 12 and in the power saving mode of FIG. 13according to an exemplary embodiment of the inventive concept.

FIG. 15 is a flowchart for describing a method of displaying an image inthe receive mode and in the power saving mode of FIG. 5 according to anexemplary embodiment of the inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the inventive concept provide a display drivercircuit supporting an operation in a low power mode of a display device.

Exemplary embodiments of the inventive concept will be described indetail hereinafter with reference to the accompanying drawings. Likereference numerals may refer to like elements throughout thisapplication.

FIG. 1 is a block diagram illustrating a configuration of an electronicdevice including a display driver circuit according to an exemplaryembodiment of the inventive concept. For example, an electronic device1000 may be implemented with one of various types of electronic devicessuch as a smartphone, a tablet PC, a laptop PC, an e-book reader, an MP3player, a wearable device, etc.

The electronic device 1000 may include various electronic circuits. Forexample, the electronic circuits of the electronic device 1000 mayinclude a display device 150, an image processing block 1100, acommunication block 1200, an audio processing block 1300, a buffermemory 1400, a nonvolatile memory 1500, a user interface 1600, and amain processor 1800.

The display device 150 may receive data from an external device (e.g.,the main processor 1800). A display driver circuit 200 included in thedisplay device 150 may display an image in a display panel 300 based onthe received data. Example configurations and operations of the externaldevice, the display driver circuit 200, and the display panel 300 willbe described with reference to FIG. 2. In addition, exampleconfigurations and operations of the display device 150 will bedescribed with reference to FIGS. 3 to 15.

The image processing block 1100 may receive light through a lens 1110.An image sensor 1120 and an image signal processor 1130 included in theimage processing block 1100 may generate image data associated with anexternal subject, based on the received light.

The communication block 1200 may exchange signals with an externaldevice/system through an antenna 1210. A transceiver 1220 and a MODEM(Modulator/Demodulator) 1230 of the communication block 1200 may processsignals exchanged with the external device/system in compliance withvarious wireless communication protocols.

The audio processing block 1300 may process sound information by usingan audio signal processor 1310, thus playing and outputting audio. Theaudio processing block 1300 may receive an audio input through amicrophone 1320. The audio processing block 1300 may output the playedaudio through a speaker 1330.

The buffer memory 1400 may store data that are used in operation of theelectronic device 1000. For example, the buffer memory 1400 maytemporarily store data processed or to be processed by the mainprocessor 1800. For example, the buffer memory 1400 may include avolatile memory such as a static random access memory (SRAM), a dynamicRAM (DRAM), or a synchronous DRAM (SDRAM), and/or a nonvolatile memorysuch as a phase-change RAM (PRAM), a magneto-resistive RAM (MRAM), aresistive RAM (ReRAM), or a ferroelectric RAM (FRAM).

The nonvolatile memory 1500 may store data regardless of power supply.For example, the nonvolatile memory 1500 may include at least one ofvarious nonvolatile memories such as a flash memory, a PRAM, an MRAM, aReRAM, and a FRAM. For example, the nonvolatile memory 1500 may includea removable memory such as a secure digital (SD) card, and/or anembedded memory such as an embedded multimedia card (eMMC).

The user interface 1600 may arbitrate communication between a user andthe electronic device 1000. For example, the user interface 1600 mayinclude input interfaces such as a keypad, a button, a touch screen, atouch pad, a gyroscope sensor, a vibration sensor, or an accelerationsensor. For example, the user interface 1600 may include outputinterfaces such as a motor or an LED lamp.

The main processor 1800 may control overall operations of the componentsof the electronic device 1000. The main processor 1800 may processvarious operations of the electronic device 1000. For example, the mainprocessor 1800 may be implemented with an operation processingdevice/circuit, which includes one or more processor cores, such as ageneral-purpose processor, a special-purpose processor, an applicationprocessor, or a microprocessor.

For example, the main processor 1800 may transmit data to the displaydriver circuit 200. The display driver circuit 200 may drive the displaypanel 300 based on the data to display an image in the display panel300.

As another example, the user may set an operation mode of the displaydevice 150 through the user interface 1600. The main processor 1800 maycontrol a type of data to be transmitted to the display driver circuit200 or a speed of data to be transmitted to the display driver circuit200, depending on the operation mode set by the user. The display drivercircuit 200 may control a path where data are processed, depending onthe type of the received data or the speed of the received data.

However, the components illustrated in FIG. 1 are only exemplary, andare not intended to limit the inventive concept. The electronic device1000 may not include one or more of the components illustrated in FIG.1, or may further include at least one component not illustrated in FIG.1.

FIG. 2 is a block diagram illustrating a configuration associated with adisplay device of FIG. 1 according to an exemplary embodiment of theinventive concept.

The display device 150 may include the display driver circuit 200 andthe display panel 300. However, FIG. 2 shows only a configuration of thedisplay device 150, and the display device 150 may further includecomponents not illustrated in FIG. 2.

An external device 100 may transmit data to the display device 150. Forexample, the external device 100 may include the main processor 1800 ofFIG. 1. The external device 100 may communicate with the display device150 in compliance with an interface protocol (e.g., a mobile industryprocessor interface (MIPI) protocol) supported by the electronic device1000.

The display device 150 may display an image based on the data. Datatransmitted from the external device 100 may include at least one ofstill image data and video data (or moving image data). The externaldevice 100 may transmit data at various speeds. For example, theexternal device 100 may transmit still image data at a speed which isslower than a speed at which video data are transmitted.

The external device 100 may transmit various types of data. For example,the external device 100 may transmit image data having various sizessuch as M bits, N bits, and K bits. “M”, “N”, and “K” may be positiveintegers.

For example, when an encoder is not included in the external device 100,the external device 100 may transmit full color data which are notencoded. The full color data may include information about a color of animage to be displayed in a display panel. The full color data may beM-bit data.

As another example, when an encoder is included in the external device100, the external device 100 may transmit encoded data. The encoder mayencode the full color data to the encoded data. The encoded data may beN-bit data. In this case, “N” may be smaller than “M”.

As another example, when a compression processor is included in theexternal device 100, the external device 100 may transmit compresseddata. The compression processor may generate the compressed data byprocessing the full color data. The compressed data may be K-bit data.“K” may be smaller than “M” and “N”. An operation in which thecompressed data are generated by processing the full color data will bedescribed with reference to FIG. 4.

Since the size of the encoded data and the size of the compressed dataare smaller than the size of the full color data, power consumption whenthe external device 100 transmits the encoded data or the compresseddata may be smaller than power consumption when the external device 100transmits the full color data. In exemplary embodiments of the inventiveconcept, to reduce power consumption of the display driver circuit 200,the external device 100 may transmit the encoded data or the compresseddata.

The display driver circuit 200 may receive data from the external device100. To display an image in the display device 150, the display drivercircuit 200 may output a driving signal based on the received data.

The display driver circuit 200 may receive data at various speeds. Forexample, the external device 100 may transmit still image data and videodata at different speeds. In an exemplary embodiment of the inventiveconcept, the display driver circuit 200 may control a path where dataare processed, depending on a speed at which data are received.

The display driver circuit 200 may receive various types of data. Forexample, the display driver circuit 200 may receive the full color data,the encoded data, the compressed data, and/or the like from the externaldevice 100. The data may include information about a type of the data.In an exemplary embodiment of the inventive concept, the display drivercircuit 200 may control a path where data are processed depending on thetype of the received data, by using the information about the type ofthe data.

To control a path where data are processed, the display driver circuit200 may control some of components of the display driver circuit 200such that some of the components of the display driver circuit 200 donot operate. Accordingly, the power consumption of the display drivercircuit 200 may be reduced.

The display panel 300 may display an image which is based on datareceived by the display driver circuit 200. For example, the displaypanel 300 may be implemented in various forms such as a crystal display(LCD) panel, a light-emitting diode (LED) display panel, an organic LED(OLED) display panel, or an active matrix OLED (AMOLED) display panel.

The display panel 300 may include a pixel array which is composed of aplurality of pixels. The pixel array may form a region which is used asa screen where an image is displayed. Pixels of the pixel array may beindependently driven by the display driver circuit 200. The displaydriver circuit 200 may drive the display panel 300 based on the drivingsignal.

The user may set an operation mode of the display device 150 through theuser interface 1600 of FIG. 1. The display device 150 may be operated invarious modes by the display driver circuit 200. In an exemplaryembodiment of the inventive concept, the display driver circuit 200 maysupport the display device 150 to operate in a low-power mode. Thelow-power mode may refer to a mode which limits a part of functions ofthe display device 150 to reduce power consumption of the display device150.

In an exemplary embodiment of the inventive concept, the low-power modemay refer to a mode of displaying a simple image in the display panel300. An image may be displayed on the display panel 300 in the low-powermode by using a combination of colors less than colors used to displayan image on the display panel 300 in a normal mode.

In an exemplary embodiment of the inventive concept, the low-power modemay be an always on display (AOD) mode. The AOD mode may be a mode whichdisplays a specific image on the display panel 300 without a continuousmanipulation of the user. For example, in the AOD mode, the displaydriver circuit 200 may display time information on a given region of thedisplay panel 300 and may display a black color in a remaining region.While the time information displayed on the display panel 300 does notchange, the display driver circuit 200 may not receive new data from theexternal device 100.

For example, the display driver circuit 200 may operate in such a waythat an image is displayed in a combination of not more than eightcolors. Additionally, while an image is displayed on the display panel300 and the displayed image does not change, the display driver circuit200 may operate without receiving data from the external device 100.Configurations and operations of the display driver circuit 200 will bedescribed with reference to FIGS. 3 to 15.

FIG. 3 is a block diagram illustrating a configuration of a displaydriver circuit of FIG. 2 according to an exemplary embodiment of theinventive concept.

The display driver circuit 200 may include an interface 210, an encoder220, a memory 230, a decoder 240, a controller 250, and a source driver260. However, FIG. 3 shows only a configuration of the display drivercircuit 200, and the display driver circuit 200 may further includecomponents not illustrated in FIG. 3. Alternatively, the display drivercircuit 200 may not include one or more of the interface 210, theencoder 220, the memory 230, the decoder 240, the controller 250, andthe source driver 260 illustrated in FIG. 3. For example, when thedisplay driver circuit 200 receives the encoded data or compressed datafrom the external device 100, the display driver circuit 200 may notinclude the encoder 220. Configurations and operations of the displaydriver circuit 200 which does not include an encoder will be describedwith reference to FIGS. 9 to 14.

The external device 100 may transmit a transmit signal for transmittingdata. The interface 210 may receive the transmit signal from theexternal device 100. The interface 210 may receive image data from theexternal device 100, based on the transmit signal. For example, theimage data may include information about an image to be displayed on thedisplay panel 300. The interface 210 may transmit the received data toany of the other components in the display driver circuit 200.

The interface 210 may receive still image data or video data. Theinterface 210 may receive data at a speed corresponding to a speed atwhich the external device 100 transmits data. The interface 210 mayreceive the still image data and the video data at different speeds. Inan exemplary embodiment of the inventive concept, the interface 210 mayreceive the still image data at a speed which is slower than a speed atwhich the video data are transmitted.

The interface 210 may receive various types of data from the externaldevice 100. For example, the received data may correspond to full colordata, encoded data, compressed data, etc. The size of the full colordata may be M bits, the size of the encoded data may be N bits, and thesize of the compressed data may be K bits. “K” may be smaller than “N”,and “N” may be smaller than “M”.

The encoder 220 may receive data from the interface 210. The encoder 220may encode the received data. For example, the full color data may beencoded from M-bit data to N-bit data.

The memory 230 may store data transmitted from the components of thedisplay driver circuit 200. The memory 230 may include a volatile and/ornonvolatile memory. For example, the memory 230 may include at least oneof a volatile memory (DRAM, SRAM, or SDRAM) and a nonvolatile memory(programmable read-only memory (PROM), erasable PROM (EPROM), flash ROM,or flash memory).

For example, the memory 230 may receive data from the interface 210 orthe encoder 220. The memory 230 may store data received from theinterface 210 or data received from the encoder 220. When the full colordata are received from the external device 100, the full color data maybe encoded before the full color data are stored in the memory 230.Accordingly, a capacity of the memory 230 may be reduced.

The decoder 240 may decode the encoded data. To decode data, the decoder240 may receive the encoded data stored in the memory 230.

For example, when the display driver circuit 200 receives the encodeddata, the display driver circuit 200 may include the decoder 240 fordecoding the encoded data. In an exemplary embodiment of the inventiveconcept, when the display driver circuit 200 includes an encoder forcompressing data, the display driver circuit 200 may include the decoder240 corresponding to a compression format of the encoder 220. Theencoded data may be decoded by the decoder 240.

For example, the size of the full color data may be larger than the sizeof encoded data. When the full color data are used in the display drivercircuit 200, power consumption of the display driver circuit 200 mayincrease. Additionally, a storage space of the memory 230 may becomeinsufficient. Accordingly, when the full color data are received fromthe external device 100, the full color data may be transmitted orreceived among components of the display driver circuit 200 in anencoded state.

The controller 250 may receive data from the external device 100.Additionally, the controller 250 may receive data stored in the memory230 or data decoded by the decoder 240. The controller 250 may processthe decoded data to generate compression data or may use data stored inthe memory 230 as compression data.

The compression data may be used to display a simple image in thelow-power mode. The size of the compression data may be smaller than thesize of the encoded data. When the compression data are used, powerconsumption of the display driver circuit 200 may be reduced.Additionally, a storage space of the memory 230 may be efficiently used.

The controller 250 may generate color data by using the compressiondata. The color data may include information about a color of an imageto be displayed on the display panel 300 in the low-power mode. Kinds ofcolors capable of being expressed by using information included in thecolor data may be smaller in number than kinds of colors capable ofbeing expressed by using information included in the full color data.Colors expressed by the color data may be based on colors expressed bythe full color data. A method of generating the full color data, thecompression data, and the color data in the controller 250 will bedescribed with reference to FIG. 4.

The above descriptions include a configuration and an operation in whichthe controller 250 generates the color data by using the compressiondata, but the inventive concept is not limited thereto. For example, thecontroller 250 may transmit the compression data to a separate imageprocessing module, instead of generating the color data by using thecompression data. The image processing module may generate the colordata by using the received compression data.

Data received from the external device 100 may include information abouta type of the data. By using the information included in the data, thecontroller 250 may operate based on the type of the data received fromthe external device 100. The controller 250 may control a path in whichthe data are processed in the display driver circuit 200, depending onthe type of the data received from the external device 100. To controlthe path where the data are processed, the controller 250 may controlthe encoder 220, the memory 230, and the decoder 240. Depending on thetype of the data received by the display driver circuit 200, thecontroller 250 may control the encoder 220 and/or the decoder 240 suchthat the encoder 220 and/or the decoder 240 do not operate. Powerconsumption of the display driver circuit 200 when the encoder 220and/or the decoder 240 does not operate is smaller than powerconsumption of the display driver circuit 200 when the encoder 220and/or the decoder 240 operates. Accordingly, the power consumption ofthe display driver circuit 200 may be reduced.

In an exemplary embodiment of the inventive concept, when the receiveddata are compressed data, the controller 250 may control the encoder 220and the decoder 240 such that the encoder 220 and the decoder 240 do notoperate. In an exemplary embodiment of the inventive concept, when thereceived data are encoded data, the controller 250 may control theencoder 220 such that the encoder 220 does not operate. An operation ofthe controller 250, which is performed according to a type of receiveddata, will be described with reference to FIGS. 6 and 15.

The controller 250 may generate a control signal. The components 210,220, 230, 240, 250, and 260 of the display driver circuit 200 mayoperate in response to the control signal. For example, the components210, 220, 230, 240, 250, and 260 of the display driver circuit 200 mayoperate in response to the control signal such that an image isdisplayed on the display panel 300.

The controller 250 may operate based on a speed at which data arereceived from the external device 100. The speed at which data arereceived may be determined based on a speed at which the control signalis generated.

For example, while an image is displayed on the display panel 300, whendata are received from the external device 100 at a slower speed than aspeed at which the control signal is generated, the controller 250 maycontrol the memory 230 such that compression data are stored in thememory 230. When the compression data are stored in the memory 230, thecontroller 250 may control the encoder 220 and the decoder 240 such thatthe encoder 220 and the decoder 240 do not operate. While new data arenot received from the external device 100, the controller 250 maygenerate color data by using the compression data stored in the memory230. An operation of the controller 250, which is performed according toa speed at which data are received from the external device 100, will bedescribed with reference to FIGS. 6 and 15.

The source driver 260 may receive the color data generated in thecontroller 250. The source driver 260 may output the driving signalbased on the color data. The source driver 260 may drive data linesconnected to the pixels of the display panel 300. The source driver 260may drive the data lines based on the driving signal. The source driver260 may receive the color data in response to the control signal and maycontrol the display panel 300 such that an image is displayed on thedisplay panel 300.

FIG. 4 is a conceptual diagram for describing a method of processingfull color data to generate compression data and color data in acontroller of FIG. 3 according to an exemplary embodiment of theinventive concept.

The display device 150 may be operated in the low-power mode by thedisplay driver circuit 200. An image may be displayed on the displaypanel 300 in the low-power mode by using a combination of colors lessthan colors used to display an image on the display panel 300 in thenormal mode, For example, in the low-power mode, an image may bedisplayed on the display panel 300 by using a combination of not morethan eight colors.

A description will be given where the display device 150 displays animage in the low-power mode by using a combination of not more thaneight colors, but the inventive concept is not limited thereto. Thedisplay device 150 according to exemplary embodiments of the inventiveconcept may display an image by using a combination of two colors (blackand white) in the low-power mode, or may display an image by using acombination of more than eight colors.

The controller 250 may receive decoded data from the decoder 240. Forexample, the decoded data may be the full color data.

Referring to drawing 410, the full color data may be composed of colorstreams 411, 412, and 413 of red “R”, green “G”, and blue “B”,respectively. Each of the color streams 411, 412, and 413 may becomposed of eight bits. Accordingly, information about 256 colors may bestored in only the one red color stream 411. Since an image may bedisplayed on the display panel 300 by using a combination of not morethan eight colors in the low-power mode, not all eight bits in each ofthe color streams 411, 412, and 413 may be needed.

The controller 250 may generate compression data by using bit values ofthe color streams 411, 412, and 413. Bits included in the compressiondata may be selected from bits included in the color streams 411, 412,and 413. Referring to drawing 414 and drawing 420, the controller 250may generate the compression data by using most significant bit (MSB)values of the color streams 411, 412, and 413. Since the full color datainclude three color streams, the compression data may be composed ofthree bits.

However, the inventive concept is not limited thereto. For example, thefull color data may include “x” color streams, and one color stream maybe composed of “y” bits. The compression data may be generated by using“z” bits of the “y” bits in each color stream. Here, “x”, “y”, and “z”may be any integer, and “z” may be smaller than “y”.

The controller 250 may generate color data by using bit values of thecompression data. The controller 250 may generate the color data byenumerating all or some of the bit values of the compression data.Referring to drawing 420 and drawing 430, the color data may begenerated by enumerating bits of the compression data eight times. Asize of the color data may be identical to a size of the full colordata. However, information about a color capable of being expressed byusing the color data may be smaller in size than information about acolor capable of being expressed by using the full color data.

For example, the full color data may express 256 colors by using onecolor stream. Since three color streams are included in the full colordata, the full color data may express “256*256*256” colors. In contrast,the color data may express 2 colors by using one color stream. The colordata may express “2*2*2” colors by using three color streams.

A method of processing the full color data to generate compressed datain a compression processor included in the external device 100 may beidentical or similar to a method of processing the full color data togenerate the compression data in the controller 250. Thus, thecompressed data and the compression data which are generated based onthe same full color data may include the same information.

Accordingly, when data received from the external device 100 arecompressed data, the controller 250 may not generate separatecompression data and may use the compressed data as the compressiondata.

FIG. 5 is a conceptual diagram for describing a receive mode and a powersaving mode of a display driver circuit according to an exemplaryembodiment of the inventive concept.

For example, in the low-power mode in which an image is displayed byusing a combination of not more than eight colors, the display drivercircuit 200 may operate in a receive mode or in a power saving modedepending on a speed at which data are received.

In FIG. 5, an example waveform of a control signal cs is illustrated.The control signal cs may be generated by the controller 250. Thedisplay driver circuit 200 may operate in response to the control signalcs. For example, the display driver circuit 200 may receive data fromthe external device 100 in response to the control signal cs. As anotherexample, the display driver circuit 200 may operate in response to thecontrol signal cs such that an image is displayed on the display panel300. The receive mode and the power saving mode will be described withregard to the control signal cs.

In the receive mode, the display driver circuit 200 may receive datafrom the external device 100 at a speed corresponding to a speed atwhich the control signal cs is generated. For example, the speed atwhich data are received from the external device 100 may besubstantially identical to the speed at which the control signal cs isgenerated.

The display driver circuit 200 may receive first data in response to asignal cs1. A first image 510 may be displayed based on the first data.The display driver circuit 200 may receive second data in response to asignal cs2. A second image 520 may be displayed based on the seconddata.

Third data for displaying a third image 530 may not be transmitted fromthe external device 100. When the third data are not received inresponse to a signal cs3, the display driver circuit 200 may use thesecond data to display the third image 530. After the third image 530 isdisplayed based on the second data, the display driver circuit 200 mayoperate in the power saving mode.

In the power saving mode, while an image is displayed on the displaypanel 300, the display driver circuit 200 may not receive data from theexternal device 100. While data are not received from the externaldevice 100, the display driver circuit 200 may operate such that animage is displayed by using the data received in the receive mode. Forexample, until a signal cs6 is generated after the signal cs3 isgenerated, the display driver circuit 200 may not receive data from theexternal device 100. A fourth image 540, a fifth image 550, and a sixthimage 560 may be displayed based on the second data.

After the signal cs6 is generated, when data are received from theexternal device 100, the display driver circuit 200 may operate in thereceive mode.

For example, the controller 250 may generate the signals cs1 to cs6every reference time interval, and a reference time may be providedbetween the signals cs1 to cs6. For example, when following (orsubsequent) data are received within the reference time after precedingdata are received (e.g., in the case where a speed at which data arereceived is fast), the display driver circuit 200 may operate in thereceive mode. In contrast, when the following data are not receivedwithin the reference time after the preceding data are received (e.g.,in the case where a speed of receiving data is slow), the display drivercircuit 200 may operate in the power saving mode.

FIG. 6 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving full color data from anexternal device according to an exemplary embodiment of the inventiveconcept. For better understanding, FIG. 5 will be referenced togetherwith FIG. 6.

In the descriptions with reference to FIGS. 6 to 8, an operation of anexternal device 100 a may be identical or similar to the operation ofthe external device 100 described with reference to FIG. 2. Componentsof a display driver circuit 200 a may operate to be identical or similarto the components 210, 220, 230, 240, 250, and 260 of the display drivercircuit 200 of FIG. 3.

In the descriptions with reference to FIGS. 6 to 8, the second datareceived from the external device 100 a may be the full color data. Thefull color data may be M-bit data. However, the inventive concept is notlimited to the case where the second data are the full color data.

The interface 210 may receive the second data from the external device100 a.

In operation “a1”, the interface 210 may transmit the second datareceived from the external device 100 a to the controller 250. Thecontroller 250 may control operations of the encoder 220 and the decoder240, depending on a type of the second data received. When the seconddata are the full color data, the controller 250 may control the encoder220 and the decoder 240 such that the encoder 220 and the decoder 240operate.

In operation “a2”, the interface 210 may transmit the full color data tothe encoder 220. The encoder 220 may encode the full color data. Theencoded data may be N-bit data.

In operation “a3”, the memory 230 may store the data encoded by theencoder 220.

In operation “a4”, the decoder 240 may decode the data stored in thememory 230. The decoded data may be the full color data.

In operation “a5”, depending on the method described with reference toFIG. 4, the controller 250 may generate compression data by using thefull color data. The compression data may be K-bit data. Additionally,the controller 250 may generate color data by using the compressiondata. The color data may be M-bit data.

In operation “a6”, the controller 250 may output the color data to thesource driver 260. The source driver 260 may receive the color data inresponse to the signal cs2. The source driver 260 may output the drivingsignal based on the color data. Depending on the driving signal, thesource driver 260 may control the display panel 300 such that the secondimage 520 is displayed on the display panel 300.

When the third data are not received in response to the signal cs3, thedata stored in the memory 230 in operation “a3” may be again used todisplay the third image 530. The display driver circuit 200 a maydisplay the third image 530 in the display panel 300 by repeating someof the operations performed to display the second image 520 in thedisplay panel 300. The third image 530 may be displayed on the displaypanel 300 through operation “a4” to operation “a6”.

FIG. 7 is a block diagram for describing an operation of processing datain a power saving mode after full color data are received from anexternal device according to an exemplary embodiment of the inventiveconcept. For better understanding, FIG. 5 will be referenced togetherwith FIG. 7.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode. In the power saving mode, the controller 250may control the encoder 220 and the decoder 240 such that the encoder220 and the decoder 240 do not operate.

In operation “a7”, the controller 250 may control the memory 230 suchthat the compression data generated in the receive mode are stored inthe memory 230. The compression data may be stored in the memory 230.The compression data stored in the memory 230 may be K-bit data.

In operation “a8”, the controller 250 may use the compression datastored in the memory 230 to display the fourth image 540 in response tothe signal cs4. Depending on the method described with reference to FIG.4, the controller 250 may generate the color data by using thecompression data.

When the compression data have been stored in the memory 230, thecontroller 250 may process the compression data stored in the memory 230without intervention of the decoder 240 and may generate the color data.When an image is displayed on the display panel 300 based on the colordata, the decoder 240 may not operate. Accordingly, the powerconsumption of the display driver circuit 200 a may be reduced. However,kinds of colors capable of being expressed based on the color data maybe smaller in number than kinds of colors capable of being expressedbased on the full color data.

In operation “a9”, the controller 250 may output the color data to thesource driver 260. The color data generated in operation “a8” mayinclude the same information as the color data generated in operation“a5”. Accordingly, the fourth image 540 may be displayed identically tothe second image 520.

In operation “a7”, the compression data stored in the memory 230 may beused to display the fifth image 550 and the sixth image 560 in responseto the signals cs5 and cs6, respectively. The display driver circuit 200a may display the fifth image 550 and the sixth image 560 in the displaypanel 300 by repeating some of the operations performed to display thefourth image 540 in the display panel 300. The fifth image 550 and thesixth image 560 may be displayed one by one in the display panel 300whenever operation “a8” and operation “a9” are repeated.

FIG. 8 is a timing diagram for describing an operation of a controllerin the receive mode of FIG. 6 and in the power saving mode of FIG. 7according to an exemplary embodiment of the inventive concept. Forbetter understanding, FIGS. 6 and 7 will be referenced together withFIG. 8.

When data are transmitted from the external device 100 a to theinterface 210, the external device 100 a may transmit a transmit signalps. For example, when transmit signals ps1, ps2, and ps3 are received,the interface 210 may receive the first data, the second data, and thethird data, respectively. Accordingly, when the transmit signals ps1 andps2 are received, the display driver circuit 200 a may operate in thereceive mode. The display driver circuit 200 a may operate in the powersaving mode from a time when the transmit signal ps2 is received to atime when the transmit signal ps3 is received.

Depending on a speed at which data are received, the display drivercircuit 200 a may repeat an operation in the power saving mode and anoperation in the receive mode. For example, when the transmit signal ps3is received, the display driver circuit 200 a may again operate in thereceive mode. Additionally, when a new transmit signal is not receivedduring the reference time after the transmit signal ps3 is received, thedisplay driver circuit 200 a may again operate in the power saving mode.

The controller 250 may operate in response to the control signal csbased on a speed at which data are received from the external device 100a.

In the receive mode, the display driver circuit 200 a may performoperation “a1” to operation “a6” in response to the signal cs2. When thesecond data are received, the second image 520 may be displayed on thedisplay panel 300 through operation “a1” to operation “a6”. As in theabove description, when the first data are received, the first image 510may be displayed on the display panel 300 through operation “a1” tooperation “a6”.

When new data in response to the signal cs3 are not received from theexternal device 100 a, the display driver circuit 200 a may performoperation “a4” to operation “a6” in response to the signal cs3. In thiscase, since the second data stored in the memory 230 are used, operation“a1” to operation “a3” may be omitted. The third image 530 which isbased on the second data may be displayed on the display panel 300through operation “a4” to operation “a6”.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode. In the power saving mode, the controller 250may control the encoder 220 and the decoder 240 such that the encoder220 and the decoder 240 do not operate. Since the compression datagenerated in operation “a5” are used in the power saving mode, theencoder 220 and the decoder 240 may not operate.

In the power saving mode, the controller 250 may control the memory 230in response to the signal cs4 such that the compression data generatedin operation “a5” are stored in the memory 230. In operation “a7”, thecompression data generated in operation “a5” may be stored in the memory230 under control of the controller 250. The controller 250 may performoperation “a8” and operation “a9” by using the compression data storedin the memory 230. Through operation “a7” to operation “a9”, the fourthimage 540 may be displayed based on the second data.

In the power saving mode, the controller 250 may repeat operation “a8”and operation “a9” in response to the signals cs5 and cs6. Thecontroller 250 may repeat operation “a8” and operation “a9” in responseto the control signal cs, until new data are received from the externaldevice 100 a.

FIG. 9 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving encoded data from anexternal device according to an exemplary embodiment of the inventiveconcept. For better understanding, FIG. 5 will be referenced togetherwith FIG. 9.

In descriptions of FIGS. 9 to 11, as an exemplary embodiment of theexternal device 100, an external device 100 b may include an encoder110. The full color data may be encoded to encoded data by the encoder110. The external device 100 b may transmit the encoded data. Theencoded data may be N-bit data. The second data received from theexternal device 100 b may be the encoded data. However, the inventiveconcept is not limited to the case where the second data are the encodeddata.

When the encoded data are received from the external device 100 b, theencoded data received from the external device 100 b may be stored inthe memory 230 without encoding. In this case, the encoder 220 of FIG. 6may be controlled not to always operate.

In descriptions with reference to FIGS. 9 to 11, as an exemplaryembodiment of the display driver circuit 200, a display driver circuit200 b may not include the encoder 220. Components of the display drivercircuit 200 b may operate to be identical or similar to the components210, 230, 240, 250, and 260 of the display driver circuit 200 of FIG. 3.

In operation “b1”, the interface 210 may transmit the second datareceived from the external device 100 b to the controller 250. Thecontroller 250 may control an operation of the decoder 240, depending ona type of the second data received. When the second data are encodeddata, the controller 250 may control the decoder 240 such that thedecoder 240 operates.

In operation “b2”, the memory 230 may store data received from theinterface 210.

In operation “b3”, the decoder 240 may decode the data stored in thememory 230. The decoded data may be the full color data. The decodeddata may be M-bit data.

In operation “b4”, depending on the method described with reference toFIG. 4, the controller 250 may generate compression data by using thefull color data. The compression data may be K-bit data. Additionally,the controller 250 may generate color data by using the compressiondata. The color data may be M-bit data.

In operation “b5”, the controller 250 may output the color data to thesource driver 260. The source driver 260 may receive the color data inresponse to the signal cs2. The source driver 260 may output the drivingsignal based on the color data. Depending on the driving signal, thesource driver 260 may control the display panel 300 such that the secondimage 520 is displayed on the display panel 300.

When the third data are not received in response to the signal cs3, thedata stored in the memory 230 in operation “b2” may be again used todisplay the third image 530. The display driver circuit 200 b maydisplay the third image 530 in the display panel 300 by repeating someof the operations performed to display the second image 520 in thedisplay panel 300. The third image 530 may be displayed on the displaypanel 300 through operation “b3” to operation “b5”.

FIG. 10 is a block diagram for describing a method of processing data ina power saving mode after encoded data are received from an externaldevice according to an exemplary embodiment of the inventive concept.For better understanding, FIG. 5 will be referenced together with FIG.10.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode. In the power saving mode, the controller 250may control the decoder 240 such that the decoder 240 does not operate.

In operation “b6”, the controller 250 may control the memory 230 suchthat the compression data generated in the receive mode are stored inthe memory 230. The compression data may be stored in the memory 230.The compression data stored in the memory 230 may be K-bit data.

In operation “b7”, the controller 250 may use the compression datastored in the memory 230 to display the fourth image 540 in response tothe signal cs4. Depending on the method described with reference to FIG.4, the controller 250 may generate the color data by using thecompression data.

In operation “b8”, the controller 250 may output the color data to thesource driver 260. The color data generated in operation “b8” mayinclude the same information as the color data generated in operation“b4”. Accordingly, the fourth image 540 may be displayed identically tothe second image 520.

The compression data stored in the memory 230 in operation “b6” may beused to display the fifth image 550 and the sixth image 560 in responseto the signals cs5 and cs6, respectively. The display driver circuit 200b may display the fifth image 550 and the sixth image 560 in the displaypanel 300 by repeating some of the operations performed to display thefourth image 540 in the display panel 300. The fifth image 550 and thesixth image 560 may be displayed one by one in the display panel 300whenever operation “b7” and operation “b8” are repeated.

FIG. 11 is a timing diagram for describing an operation of thecontroller in the receive mode of FIG. 9 and in the power saving mode ofFIG. 10 according to an exemplary embodiment of the inventive concept.For better understanding, FIGS. 9 and 10 will be referenced togetherwith FIG. 11.

The transmit signal ps may be transmitted when data are transmitted fromthe external device 100 b to the interface 210. For example, when thetransmit signals ps1, ps2, and ps3 are received, the interface 210 mayreceive the first data, the second data, and the third data,respectively. Accordingly, when the transmit signals ps1 and ps2 arereceived, the display driver circuit 200 b may operate in the receivemode. The display driver circuit 200 b may operate in the power savingmode from a time when the transmit signal ps2 is received to a time whenthe transmit signal ps3 is received.

Depending on a speed at which data are received, the display drivercircuit 200 b may repeat an operation in the power saving mode and anoperation in the receive mode. For example, when the transmit signal ps3is received, the display driver circuit 200 b may again operate in thereceive mode. Additionally, when a new transmit signal is not receivedduring the reference time after the transmit signal ps3 is received, thedisplay driver circuit 200 b may again operate in the power saving mode.In the receive mode, the display driver circuit 200 b may performoperation “b1” to operation “b5” in response to the signal cs2. When thesecond data are received, the second image 520 may be displayed on thedisplay panel 300 through operation “b1” to operation “b5”. As in theabove description, when the first data are received, the first image 510may be displayed on the display panel 300 through operation “b1” tooperation “b5”.

When new data in response to the signal cs3 are not received from theexternal device 100 b, the display driver circuit 200 b may performoperation “b3” to operation “b5” in response to the signal cs3. In thiscase, since the second data stored in the memory 230 are used, operation“b1” and operation “b2” may be omitted. The third image 530 which isbased on the second data may be displayed on the display panel 300through operation “b3” to operation “b5”.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode. In the power saving mode, the controller 250may control the decoder 240 such that the decoder 240 does not operate.Since the compression data generated in operation “b4” are used in thepower saving mode, the decoder 240 may not operate.

In the power saving mode, the controller 250 may control the memory 230in response to the signal cs4 such that the compression data generatedin operation “b4” are stored in the memory 230. In operation “b6”, thecompression data generated in operation “b4” may be stored in the memory230 under control of the controller 250. The controller 250 may performoperation “b7” and operation “b8” by using the compression data storedin the memory 230. Through operation “b6” to operation “b8”, the fourthimage 540 may be displayed based on the second data.

In the power saving mode, the controller 250 may repeat operation “b7”and operation “b8” depending on each of the signals cs5 and cs6. Thecontroller 250 may repeat operation “b7” and operation “b8” in responseto the control signal cs, until new data are received from the externaldevice 100 b.

FIG. 12 is a conceptual diagram for describing an operation of a displaydriver circuit in a receive mode for receiving compressed data from anexternal device according to an exemplary embodiment of the inventiveconcept. For better understanding, FIG. 5 will be referenced togetherwith FIG. 12.

In the descriptions with reference to FIGS. 12 to 14, as an exemplaryembodiment of the external device 100, an external device 100 c mayinclude a compression processor 120. The compression processor 120 mayprocess full color data to generate compressed data. The compressionprocessor 120 may generate the compressed data in a method which isidentical or similar to the method in which the controller 250 generatesthe compression data. The compressed data may be K-bit data. Theexternal device 100 c may transmit the compressed data. The second datareceived from the external device 100 c may be the compressed data.However, the inventive concept is not limited to the case where thesecond data are the compressed data.

When the compressed data are received from the external device 100 c,the compressed data received from the external device 100 c may bestored in the memory 230 without encoding. In this case, the encoder 220of FIG. 6 may be controlled not to always operate. In the descriptionswith reference to FIGS. 12 to 14, as an exemplary embodiment of thedisplay driver circuit 200, a display driver circuit 200 c may notinclude the encoder 220. Components of the display driver circuit 200 cmay operate to be identical or similar to the components 210, 230, 240,250, and 260 of the display driver circuit 200 of FIG. 3.

The external device 100 c may include the compression processor 120. Thecompression processor 120 may process full color data to generatecompressed data. The compressed data may be generated in a method whichis identical or similar to the method in which the controller 250generates the compression data. The compressed data may be K-bit data.The external device 100 c may transmit the compressed data.

In operation “c1”, the interface 210 may transmit the second datareceived from the external device 100 c to the controller 250. Thecontroller 250 may control an operation of the decoder 240, depending ona type of the second data received. When the second data are thecompressed data, the controller 250 may control the decoder 240 suchthat the decoder 240 does not operate. Referring to the method describedwith reference to FIG. 4, the compressed data may be converted to colordata without a decoding process.

In operation “c2”, the memory 230 may store data received from theinterface 210.

In operation “c3”, the controller 250 may not generate separatecompression data. The controller 250 may use the compressed data storedin the memory 230 as the compression data. Depending on the methoddescribed with reference to FIG. 4, the controller 250 may generate thecolor data by using the compression data. The color data may be M-bitdata.

In operation “c4”, the controller 250 may output the color data to thesource driver 260. The source driver 260 may receive the color data inresponse to the signal cs2. The source driver 260 may output the drivingsignal based on the color data. Depending on the driving signal, thesource driver 260 may control the display panel 300 such that the secondimage 520 is displayed on the display panel 300.

When the third data are not received in response to the signal cs3, thedata stored in the memory 230 in operation “c2” may be again used todisplay the third image 530. The display driver circuit 200 c maydisplay the third image 530 in the display panel 300 by repeating someof the operations performed to display the second image 520 in thedisplay panel 300. The third image 530 may be displayed on the displaypanel 300 through operation “c3” and operation “c4”.

FIG. 13 is a block diagram for describing a method of processing data ina power saving mode after compressed data are received from an externaldevice according to an exemplary embodiment of the inventive concept.For better understanding, FIG. 5 will be referenced together with FIG.13.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode.

In operation “c5”, the controller 250 may use compression data stored inthe memory 230 to display the fourth image 540 in response to the signalcs4. Depending on the method described with reference to FIG. 4, thecontroller 250 may generate the color data by using the compressiondata.

In operation “c6”, the controller 250 may output the color data to thesource driver 260. The color data generated in operation “c6” mayinclude the same information as the color data generated in operation“c3”. Accordingly, the fourth image 540 may be displayed identically tothe second image 520.

The compression data stored in the memory 230 in operation “c2” may beused to display the fifth image 550 and the sixth image 560 in responseto the signals cs5 and cs6, respectively. The display driver circuit 200c may display the fifth image 550 and the sixth image 560 in the displaypanel 300 by repeating some of the operations performed to display thefourth image 540 in the display panel 300. The fifth image 550 and thesixth image 560 may be displayed one by one in the display panel 300whenever operation “c5” and operation “c6” are repeated.

FIG. 14 is a timing diagram for describing an operation of thecontroller in the receive mode of FIG. 12 and in the power saving modeof FIG. 13 according to an exemplary embodiment of the inventiveconcept. For better understanding, FIGS. 12 and 13 will be referencedtogether with FIG. 14.

When data are transmitted from the external device 100 c to theinterface 210, the external device 100 c may transmit the transmitsignal ps. For example, when the transmit signals ps1, ps2, and ps3 arereceived, the interface 210 may receive the first data, the second data,and the third data, respectively. Accordingly, when the transmit signalsps1 and ps2 are received, the display driver circuit 200 c may operatein the receive mode. The display driver circuit 200 c may operate in thepower saving mode from a time when the transmit signal ps2 is receivedto a time when the transmit signal ps3 is received.

Depending on a speed at which data are received, the display drivercircuit 200 c may repeat an operation in the power saving mode and anoperation in the receive mode. For example, when the transmit signal ps3is received, the display driver circuit 200 c may again operate in thereceive mode. Additionally, when a new transmit signal is not receivedduring the reference time after the transmit signal ps3 is received, thedisplay driver circuit 200 c may again operate in the power saving mode.In the receive mode, the display driver circuit 200 c may performoperation “c1” to operation “c4” depending on the signal cs2. The secondimage 520 may be displayed on the display panel 300 through operation“c1” to operation “c4”.

When new data in response to the signal cs3 are not received from theexternal device 100 c, the display driver circuit 200 c may performoperation “c3” and operation “c4” depending on the signal cs3. In thiscase, since the second data stored in the memory 230 are used, operation“c1” and operation “c2” may be omitted. The third image 530 which isbased on the second data may be displayed on the display panel 300through operation “c3” and operation “c4”.

After the third image 530 is displayed, the controller 250 may operatein the power saving mode. For example, the controller 250 may performoperation “c5” and operation “c6” by using the data stored in the memory230 in operation “c2”. As another example, in operation “c8”, thecontroller 250 may control the memory 230 such that the compression datain operation “c3” are stored in the memory 230. The controller 250 mayperform operation “c5” and operation “c6” by using the compression datastored in the memory 230 in operation “c8”. The fourth image 540 whichis based on the second data may be displayed through operation “c5” andoperation “c6”. In the power saving mode, the controller 250 mayrepeatedly perform operation “c5” and operation “c6” depending on thesignals cs5 and cs6. The controller 250 may repeatedly perform operation“c5” and operation “c6” depending on the control signal cs, until newdata are received from the external device 100 c.

FIG. 15 is a flowchart for describing a method of displaying an image inthe receive mode and in the power saving mode of FIG. 5 according to anexemplary embodiment of the inventive concept. For better understanding,FIGS. 6 to 14 will be referenced together with FIG. 15.

In operation S110, the interface 210 may transmit data received from theexternal device 100 to the controller 250. The received data may includeinformation about a type of the received data.

In operation S120, the controller 250 may control the encoder 220 andthe decoder 240, depending on the type of the received data. Forexample, the display driver circuit 200 may control the encoder 220 andthe decoder 240, depending on the type of the second data.

For example, when the second data are the full color data, thecontroller 250 may control the encoder 220 and the decoder 240 such thatthe encoder 220 and the decoder 240 operate. As another example, whenthe second data are the encoded data, the controller 250 may control theencoder 220 such that the encoder 220 does not operate. Additionally,the controller 250 may control the decoder 240 such that the decoder 240does not operate. As another example, when the second data are thecompressed data, the controller 250 may control the encoder 220 and thedecoder 240 such that the encoder 220 and the decoder 240 do notoperate.

Accordingly, in the receive mode, power consumption of the displaydriver circuit 200 when data received from the external device 100 arethe encoded data may be smaller than power consumption of the displaydriver circuit 200 when data received from the external device 100 arethe full color data. In the receive mode, power consumption of thedisplay driver circuit 200 when data received from the external device100 are the compressed data may be smaller than power consumption of thedisplay driver circuit 200 when data received from the external device100 are the encoded data.

In operation S130, the display driver circuit 200 may display an imagebased on the received data. The display driver circuit 200 may operatein response to the control signal cs.

For example, when the second data are the full color data, the displaydriver circuit 200 may perform operation “a2” to operation “a6” todisplay the second image 520 in response to the signal cs2. As anotherexample, when the second data are the encoded data, the display drivercircuit 200 may perform operation “b2” to operation “b5” to display thesecond image 520 in response to the signal cs2. As another example, whenthe second data are the compressed data, the display driver circuit 200may perform operation “c2” to operation “c4” to display the second image520 in response to the signal cs2.

In operation S140, the controller 250 may determine whether new data arereceived from the external device 100, based on the control signal cs.For example, it may be determined whether new data are received from theexternal device 100 in response to the control signal cs3.

When new data are received from the external device 100 in response to acontrol signal (S140: Yes), the display driver circuit 200 may return tooperation S110.

When new data are not received from the external device 100 in responseto a control signal (S140: No), the display driver circuit 200 maydisplay an image based on the received data. For example, the displaydriver circuit 200 may display the third image 530, based on the seconddata.

For example, when the second data are the full color data, the displaydriver circuit 200 may perform operation “a4” to operation “a6” todisplay the third image 530 in response to the signal cs3. As anotherexample, when the second data are the encoded data, the display drivercircuit 200 may perform operation “b2” to operation “b5” to display thethird image 530 in response to the signal cs3. As another example, whenthe second data are the compressed data, the display driver circuit 200may perform operation “c3” and operation “c4” to display the third image530 in response to the signal cs3.

In operation S160, the controller 250 may control the memory 230 basedon the type of the received data such that the compression data arestored in the memory 230. The compression data stored in the memory 230may be used to display the fourth image 540 while new data are notreceived from the external device 100.

For example, when the second data are the full color data, thecontroller 250 may generate the compression data in operation “a5”. Inoperation “a6”, the controller 250 may control the memory 230 such thatthe compression data are stored in the memory 230. As another example,when the second data are the encoded data, the controller 250 maygenerate the compression data in operation “b4”. In operation “b5”, thecontroller 250 may control the memory 230 such that the compression dataare stored in the memory 230. As another example, when the second dataare the compressed data, the display driver circuit 200 may use thecompressed data stored in the memory 230 as the compression data withoutgenerating separate compression data. The controller 250 may use thecompression data stored in the memory 230 without an operation ofcontrolling the memory 230 such that the compression data are stored inthe memory 230.

In operation S170, when new data are not received from the externaldevice 100 in response to a control signal, the controller 250 maycontrol the encoder 220 and the decoder 240. The controller 250 maycontrol the encoder 220 and the decoder 240 such that the encoder 220and the decoder 240 do not operate.

In operation S180, the controller 250 may determine whether new data arereceived from the external device 100, based on the control signal cs.For example, it may be determined whether new data are received from theexternal device 100 in response to the signal cs4.

When new data are received from the external device 100 in response to acontrol signal (S180: Yes), the display driver circuit 200 may return tooperation S110.

When new data are not received from the external device 100 in responseto a control signal (S180: No), in operation S190, the display drivercircuit 200 may display an image based on the received data. Forexample, the display driver circuit 200 may display the fourth image540, based on the second data.

For example, when the second data are the full color data, the displaydriver circuit 200 may perform operation “a8” and operation “a9” todisplay the fourth image 540 in response to the signal cs4. As anotherexample, when the second data are the encoded data, the display drivercircuit 200 may perform operation “b7” and operation “b8” to display thefourth image 540 in response to the signal cs4. As another example, whenthe second data are the compressed data, the display driver circuit 200may perform operation “c5” and operation “c6” to display the fourthimage 540 in response to the signal cs4.

As described above, according to exemplary embodiments of the inventiveconcept, in a low-power mode, some components in a display drivercircuit may be controlled not to operate. Accordingly, power consumptionof the display driver circuit may be reduced.

While the inventive concept has been described with reference toexemplary embodiments thereof, it will be apparent to those of ordinaryskill in the art that various changes and modifications may be madethereto without departing from the spirit and scope of the inventiveconcept as set forth in the following claims.

What is claimed is:
 1. A display driver circuit configured to drive a display panel, the display driver circuit comprising: a memory configured to store first data based on data from outside of the display driver circuit; a decoder circuit configured to decode the stored first data in a first mode; and a controller circuit configured to generate compression data using the decoded first data in the first mode, wherein, after a first image based on the compression data is displayed on the display panel in response to a first control signal and the first image is displayed on the display panel repeatedly in response to a second control signal and until second data based on the data from the outside are stored in the memory in response to a third control signal, the controller circuit is further configured to control the decoder circuit to a second mode, wherein the first data and the second data are different, wherein the second control signal is generated by the controller circuit after the first control signal is generated by the controller circuit, and the third control signal is generated by the controller circuit after the second control signal is generated.
 2. The display driver circuit of claim 1, wherein: the controller circuit is further configured to generate the compression data such that a size of the compression data is smaller than a size of the decoded first data.
 3. The display driver circuit of claim 1, wherein: bits included in the compression data are selected from bits included in the decoded first data.
 4. The display driver circuit of claim 1, wherein: while the first image is displayed on the display panel, when the second data are not stored in the memory after the first data are stored in the memory, the controller circuit is further configured to generate color data using the compression data stored in the memory and to operate such that the first image is maintained on the display panel using the color data.
 5. The display driver circuit of claim 4, wherein: all or some of bits included in the color data are obtained from bits included in the compression data.
 6. The display driver circuit of claim 4, wherein: colors expressed by the color data are based on colors expressed by the decoded first data.
 7. The display driver circuit of claim 1, wherein when the second data are stored in the memory after the first data are stored in the memory, the controller circuit is further configured to control the decoder circuit to the first mode.
 8. The display driver circuit of claim 7, wherein: when the second data are stored in the memory after the first data are stored in the memory, the decoder circuit is further configured to be controlled to the first mode and to decode the stored second data, and the controller circuit is further configured to generate new compression data using the decoded second data and to operate such that a second image is displayed on the display panel using the decoded second data.
 9. The display driver circuit of claim 7, wherein: power consumption of the display driver circuit in the second mode is smaller than power consumption of the display driver circuit in the first mode.
 10. A display driver circuit configured to drive a display panel, the display driver circuit comprising: a memory configured to store first data from outside of the display driver circuit; a decoder circuit configured to decode the stored first data in a first mode; and a controller circuit configured to control the memory and the decoder circuit based on the first data from the outside, wherein, when a size of the first data from the outside corresponds to a size of compression data, the controller circuit is further configured to control the decoder circuit to a second mode and to control the memory such that a first image is displayed on the display panel using the stored first data without the compression data, wherein, when the size of the first data from the outside does not correspond to the size of the compression data, the controller circuit is further configured to control the decoder circuit depending on a speed at which data are received from the outside after the first data, and wherein the size of the compression data is a predetermined size.
 11. The display driver circuit of claim 10, wherein: the controller circuit is further configured to generate color data using the stored first data and to operate such that the first image is displayed on the display panel using the color data.
 12. The display driver circuit of claim 10, wherein: when second data are received from the outside within a reference time after the first data are received from the outside, the controller circuit is further configured to control the decoder circuit to the first mode and to decode the second data, and to generate third data having the size of the compression data using the decoded second data.
 13. The display driver circuit of claim 12, wherein: when the second data are received from the outside within the reference time after the first data are received from the outside, the controller circuit is further configured to operate such that a second image is displayed on the display panel using the third data.
 14. The display driver circuit of claim 10, wherein: when second data are not received from the outside within a reference time after the first data are received from the outside, the controller circuit is further configured to: control the decoder circuit to operate in the second mode; generate fourth data having the size of the compression data using the decoded first data, and; control the memory such that the fourth data are stored in the memory.
 15. The display driver circuit of claim 14, wherein: when the second data are not received from the outside within the reference time after the first data are received from the outside, the controller circuit is further configured to generate color data using the stored fourth data, and to operate such that a second image is displayed on the display panel using the color data. 